Tensile structures are increasingly used as a means of protection against the weather in publicly used spaces. This is because the support structure and fabric membrane is pre-fabricated and assembled on site.The fundamental rule for stability is that, a tensioned fabric structure must curve equally in opposite directions; this gives the canopy its 3-dimensional stability. The fabric is loaded during the installation process. Is it cost effective? If you compare it with concrete and steel construction, there is an economy of cost per square metre, strength and longevity with fabric. Certain fabrics can also have more stretch in one direction than in the other.   Wikipedia defines a tensile structure as "a construction  of elements carrying only tension and no compression or bending". This article is designed to give you some based knowledge about the use of fabric in such structures. Untreated cotton can be used which will burn out in a flash and will not drop hot plastics on anyone below. How is a 3-diemnsional form achieved? The complex 3-dimensional form of a canopy is achieved not by elastic fabric, but by cutting the fabric and bonding it together to make its final 3-dimensional shape.

Greater translucency and dynamic, organic shapes bring the feeling of the outside inside. A typical structural external fabric has a tensile strength of 10 tonnes per linear metre and will creep no more than a few percent after 20 years of extreme conditions. PVC coated polyester is the least expensive and has a design life of 15 to 20 years.T. They also provide shade and protection from the weather. External fabrics such as PVC  coated polyester; silicon coated glass; and Teflon coated glass P. Pre-tension is the most efficient way of resisting live loads such as snow, wind etc. This is due to velvet seat cushion the threads of the weft being woven in and out of the warp threads, which are already tightened. The main cost saving comes with a reduced installation time. What is tension? Tension is the force used to pull the molecular structure of a material apart. Silicone coated glass cloth and Teflon coated fabric has a higher tensile strength than PVC coated polyester, but is slightly more brittle. Why use fabric in tensile structures? Fabric can facilitates greater spans than conventional building materials, with a minimal supporting structure.

Tensile structures are generally supported by some form of compression or bending elements (for example the  masts  in The O2, formerly the Millennium Dome.What is a tensioned fabric structure? True tensile fabric structures are those in which every part of the fabric is in tension.Will the fabric stretch over time? Fabric, being flexible and normally woven, is a 'live' medium that stretches across the diagonal plain to a greater extent than in the direction of the weave, this can be most easily seen with a piece of netting. What types of fabric can be used? There are many different fabrics with various features and benefits to each one, however there are three basic external fabric types most commonly used in tensile fabric structures. Fabric structures have been built in typhoon and tornado zones. If something is thrown onto the fabric, it will bounce off. This is called pre-tension or pre stress.

It is the most efficient way of using any material because it utilises the whole cross section at maximum efficiency rather than just the material at the extremes of the cross sectional form (fro example, as in bending and compression loads). Lycra materials can be used for awkward or ad-hoc shapes. The most commonly used is PVC coated glass cloth due to its easy maintenance and very good fire resistance polytetrafluroethylene. This is because such structures can span large distances and can be aesthetically pleasing. Are all fabrics fire retardant? All types of fabric can be used if suitably fire retardant. Is the fabric elastic? The fabric used in tensile structures is not stretchy or elastic in nature. It will not balloon under wind loads and settle under snow. Can a fabric structure cope with the weight of snow or heavy weather? A tensile fabric structure, once it is tensioned, can take a large amount of applied weight and the fabric is extraordinarily tight. They have different benefits in terms of cost and durability.

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